Landing gear comprising a steerable lower part is known. This lower part generally comprises a rod mounted slidably in a casing of the landing gear against a suspension force, the rod bearing at its lower end an axle which receives one or more wheels. This landing gear bears in certain cases a collar or a sleeve mounted rotatably on the casing of the landing gear while being connected to the steerable lower part by a torque link. The collar or the sleeve is provided with a toothed ring which cooperates with the rack of a steering actuator in order to pivot the steerable lower part. By way of example, mention will be made of the auxiliary landing gear of the AIRBUS A320 which is provided with such rack actuation.
The rack is connected at its two ends to pistons which are slidably mounted with sealing in cylinders extending on either side of the landing gear so as to define therein two chambers of a hydraulic actuator.
Often, such pistons are made entirely of bronze for reasons of simplicity. However, making them in this way proves to be cumbersome. Furthermore, if in production the outside diameter of the piston does not meet the specifications, the whole of the piston is scrapped. Likewise, if in service the piston wears to the point of no longer meeting the dimension specifications, the whole of the piston must be scrapped to be replaced by a new piston.